WASHINGTON — A member of President Trump’s legal team said Sunday that the president is not under investigation by the special counsel looking into Russia’s election-year meddling, contradicting Trump’s assertion in a Friday morning tweet that he is a subject of the widening inquiry.

The denial Sunday by Jay Sekulow, one of several personal lawyers Trump has hired to represent him in the Russia case, is the latest of many examples in which the president’s aides and lawyers have scrambled to avert a public-relations mess created by Trump’s tweets, off-script remarks, or leaked private conversations.

Advisers have been forced to perform post-presidential cleanup in the wake of Trump’s tweets and comments.

They include a claim he had been wiretapped by the Obama administration, his Oval Office remarks to Russian diplomats about the former FBI director, his private musings about the possibility of firing the Russia special counsel, his claim that there are recordings of White House conversations, and his comments about a “military” deportation operation.

Get Political Happy Hour in your inbox:

Your afternoon shot of politics, sent straight from the desk of Joshua Miller.

In Sekulow’s case, his appearance on multiple Sunday morning talk shows took on the added urgency of trying to protect his client from admitting that he is in legal jeopardy during a criminal investigation, one that appears to be increasingly focused on whether Trump took steps to interfere with the normal progress of the federal inquiry.

Rod J. Rosenstein, deputy attorney general, last month named Robert B. Mueller, a former FBI director, as a special counsel to lead the sprawling investigation into the extent of Russia’s meddling in the 2016 presidential election, and whether any of Trump’s associates colluded in that effort.

In addition, two congressional committees have issued subpoenas for testimony and documents as part of their wide-ranging, bipartisan investigations. All three inquiries are reportedly examining whether Trump, as president, sought to impede the progress of the inquiries.

Sekulow repeatedly and forcefully denied that Sunday, saying on CBS’s “Face the Nation” program that “the president has not been and is not under investigation,” and insisting that the administration had received no information from the special counsel’s office to think otherwise.

On CNN’s “State of the Union” program, he said flatly, “The president is not a subject or target of an investigation.”

On Friday, the president wrote the opposite on Twitter, saying: “I am being investigated for firing the FBI director by the man who told me to fire the FBI director! Witch Hunt.”

Sekulow said the message was merely a response by the president to a Washington Post article citing five unnamed sources who said Trump was under investigation in the Russia case. Sekulow said that Trump would have challenged the basic assertion of the article, but was constrained by Twitter’s limit of 140 characters per post.

“There’s a limitation on Twitter, as we all know,” Sekulow said on CNN. “And the president has a very effective utilization of social media.”

Sekulow did acknowledge on “Fox News Sunday” that he “can’t read people’s minds,” but said there had been “no notification of an investigation” of the president by Mueller.

“I can’t imagine a scenario where the president would not be aware of it,” Sekulow said on CBS. But legal analysts say few criminal investigations begin with an identified target. Rather, they are notified after evidence is developed.

Suggestions that Mueller is looking at Trump’s actions grew last week when Mueller requested interviews with three high-ranking current or former intelligence officials, according to a person briefed on the investigation.

Reports have raised questions about whether Trump requested their help in trying to get James Comey, then the FBI director, to end an inquiry into Trump’s former national security adviser, Michael Flynn.

Veteran lawyers who have represented presidents during high-stakes legal cases said Trump’s repeated comments about the Russia investigation were extremely unusual.

They said previous presidents would make sure to have the White House counsel’s office and their personal lawyers carefully review any comments about such an investigation before making them.

They said Sekulow’s denials were not so much a legal argument as an effort to repair the political damage from the apparent admission by Trump.

“With all due respect to Mr. Sekulow, what he says about what Mr. Mueller is or isn’t doing will make no difference,” said Gregory B. Craig, who led the legal team defending President Bill Clinton against impeachment charges. “If Mueller thinks there is evidence that obstruction occurred, Mueller’s job is to investigate.”

Members of both parties expressed exasperation with Trump’s continuing commentary about the Russia investigation. Senator Marco Rubio, Republican of Florida, pleaded Sunday for the president to give Mueller the room he needs to manage the inquiry.

Representative Adam Schiff, Democrat of California, accused Trump and his allies of seeking to undermine Mueller’s inquiry, setting a pretext for potentially firing those leading it. Trump has reportedly told friends that he considered firing Mueller, and the president’s tweet Friday appeared aimed at Rosenstein, raising questions about whether he might fire him, too.